Centrifugal separator



sept. 14, w26. 1,599,502 H.THOMASSEN CENTRI FUGAL S EPARATOR Filed NOV. l1, 1924 Im/@n for' ferr nuo' Thomassen /Of ornef.

lPatented Sept. 14, 1926.

PATENT 'oF/FICE."

HERMANUS THOMASSEN, F VELP, NETHE'RILANDS.

CENTRIFUGAL SEPARATQR.

Application filed November 11, 1924, Serial No. 749.186, and in Germany May 27, 1924.

My copending application for Patent Nr. 693,270 relates to a process lfor removing impurities from paper pulp or other fibrous material by'means of a centrifugal'separator running at such speed that the pulp accumulates in a substantially cylindrical layer around the axis of rotation, whereby the heavier impurities against the wall of the drum so as to remain in the separator, whereas the purified mass/ is discharged over the top edge ofthe drum; Secured to the said top edge is an inwardly projecting ring, the width ofwhicli determines .the thickness of the layer `of pulp formed and, consequently, the time during which the mass is subjected to the centrifugal action, Whereas a second ring concentric with the axis of rotation but disposed at some distance from the wall of the drum Aretains the lighter impurities. By this process it is-possible to produce 'in a mini-v mum of time perfectly pure paper pulp.

My present invention relates to a centrifugal separator which is exceptionally suitable for carrying the said process into practice. The drum of this separator consists of superposed, concentric, cylindrical .sectioiisof increasing diameter,l so that in elevation the drum is stepped. To the top 3H edge of each drum section I secure tliering,

the width of which determines the thickness of the cylindrical layer of pulp. For sep- .arating ot the lighter impurities, it suf. `fices in most cases to provide only the clipper drum seuction with al ring a certain distance inwardly from its wall, which ring maybe slightly dished or curved in cross section.`

In acentrfugal separator according to my present invention the coarse impurities are'separated out in the lowermost section of the. drum, whereas the higher sections serve to separate the smaller impurities. Such a .stepped centrifugal machine offers the advantage that the completeness of the separation can be checked by the absence (if-impurities against thev inner wall ofthe top section. The annexed drawing illustrates, by way of example only, a centrifugal f'separator" 'comprising five sections, Figure 1 being a vertical section and Figure-2 a plan view ofthe machine. Figure 3 showson an enlarged scale the yertical section 0f the stepped wall-0f the drum. l

Secured to a hollow vertical shaft 1 is a bottom 2, which supports a drum consistare thrown out part of ing of five superpdsed cylindrical sections 3. The shaft l is driven bthrough mitre wheels 5, G by a-belt pulley 4. To the pulp, which is continuously supplied through a central feed pipe 7 having a flared mouth 8 a relatively small distance above the bottom 2, rapid rotary motion is imparted by vanes, arm's or impellers 9 securedto the shaft 1, whereby it is .thrown at high radial speed against the ,wall of the drum, so that by the impact part of the impurities associatedv 'with the fibres is released therefrom. In the first or Vlowermost section the pulp thus forms a cylindrical layer, the thicknessvof which corresponds to the width of the rin'g l0 secured to Athe top edge of this section.

As the pulp is ,delivered by the feed pipe 7, the partly purified mass is forced /over the lowermost ring 10 into the second drum section, whereit is again thrown against the cylindrical wall so as to release part of the after forced over this ring until the coin-ll pletely purified `mass is discharged into a stationary container 12 provided with an o utlet 13. e

One singlefring 11 placed inside thetop sectionat a small'distance from the cylindrical wall thereof retains the lighter impiirities, but.; it should be well vunderstood that two, three or more of the sections may be provided with such a ring 11. l

The gearing and the drum are enclosed by casings 14 and 15, respectively.

The number of drum sections used pends upon the percentage and the nature of the impurities present in the pulp, upon the desired quality of the purified material, etc.

i 1t Yhas been found in practice that a cengards the purifying'of the pulp than a ma-f' ordinary, i. e. non-stepped chine having an drum.

What I claim is 1. A centrifugal separator comprising a drum having superposed unperforated cylindrical sections of increasing diameter, a ring projecting inwardly from the upper' edgeof each of said sections to prevent the discharge of heavier material, and an annular member mounted in at least one of the sections of the drum to prevent the dis# charge of lighter material, and spaced from the internal wall of said section to permit the discharge of material of predetermined weight. *Y l' 2. A centrifugal separator comprising a drum having superposed unperforated sections of increasing diameter, a ring projecting inwardly from the upper edge of each of said sections to obstruct the passage of heavy materials, and an annular member mounted within the upper section and spaced from the inner wall of saidfsection and from the inwardly projecting ring 26 thereinA to obstruct the passage of lighter materials and to permit the passage of materials of medium weight.

3. A. 'centrifugal separator comprising `a drum havingsuperposed unperforated sections of increasing diameter, central feed means -for supplying the material to the lower section, an internal annular ledge formed at the upper extremity of each section to obstruct the passage of the heavier materials, an annular member mounted within the upper section and spaced from the inner wall thereof and from the adjacent annular ledge` to obstruct the passage of lighter materials, and an annular receiver for the material of medium weight passing between the said ring and the, adjacent ledge. Y p

ln testimony whereof I ax my signature.

" HERMANUS THOMASSEN. 

